A known commercial water heater is disclosed in U.S. Pat. No. 6,036,480. This storage-type water heater has a combustion burner at the top of a vertical combustion tube. A snorkel extends upward from the bottom of the combustion tube, and a coil extends downward from the top of the snorkel around the snorkel and the combustion tube. The combustion tube, snorkel and coil are all located within the water tank for transferring heat to the water. This type of water heater is sold by A. O. Smith Corporation under the trademark CYCLONE.